The first Big Advance – Cyanobacteria
It took Bacteria first to release oxygen on to the planet.
Cyanobacteria, a single celled organism, found a way of extracting the carbon from carbon dioxide, discharging oxygen as a waste product. It is thought that oxygen appeared 2.4 billion years ago. The immediate effects of the release of oxygen were an Ice Age. It is difficult to comprehend what a major event this was for our planet.
As Kartik Aiyer put it:
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A silent, mysterious force worked to release oxygen steadily, until the very composition of the atmosphere changed. That mysterious entity happened to be a microbe:
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It has become known as the Great Oxidation Event. Over time, probably millions of years, the planet became so full of oxygen that the reverse of the current global warming occurred. Just as carbon dioxide causes global warming, so oxygen causes global cooling, and the first Ice Age appeared.
Unfortunately for the existing single celled organisms, they failed to survive, because they had used gases like methane to live, now that was drowned out by oxygen, so it was probably the first Great Extinction event as well. But it paved the way for a completely new set of eukaryotic life, (more advanced life) and ultimately nearly all life as we know it today. Oxygen, the waste product, became the vital gas of life.
It is certainly no exaggeration to say that we owe our existence to cyanobacteria.
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It did more than release oxygen. Oxygen was responsible for the formation of ozone, as UV radiation from the sun split oxygen molecules into 2 atoms of oxygen, some of which reacted with another atom, to form ozone (O3). Ozone formed a barrier against harmful UV, so it was prevented from reaching the earth.
In the calculus of our Upside Down World, the tiny cyanobacteria will surely score very highly.
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In our calculus, however, there is a down side even to the action of cyanobacteria. The flooding of the then world with oxygen, caused a great Ice Age, during which most of the existing life of the earth was extinguished. So as well as the Great Oxidation Event, it can be called the First Great Extinction of Life.
Were we to be doing our calculus based on that time alone, cyanobacteria would have scored a minus quantity. It is only when we put it in historical context that it becomes a mighty plus.
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Fabulous Fungi - click here
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The Calculus - click here